This strategy is just as easy as the tacking on zeros strategy that many students find easy to remember. When you have a question like 5 x 1000, most students know that they can simply write down 5 and tack on 3 zeros because there are three zeros in a thousand, however this can also be thought of as moving the decimal to the right three places.
Since dividing is the opposite of multiplying students should be able to make this easy jump. If we move the decimal to the right when we multiply by 10, 100, 1000, then which way would it move when we divide by 10, 100, 1000? To the left is correct. When you are dividing by 10, 100, 1000 etc. you simply have to move the decimal to the left as many times as there are zeros.
Example:
23 x 10 = 2.3 (once to the left)
23 x 100 = 0.23 (twice to the left)
23 x 1000 = 0.023 (three times to the left notice we have to add a zero to show place value)
23 x 10 000 = 0.0023 (four times and again adding zeros to show place value)
Dividing by 10's 100's 100's and so on.
This strategy is just as easy as the tacking on zeros strategy that many students find easy to remember. When you have a question like 5 x 1000, most students know that they can simply write down 5 and tack on 3 zeros because there are three zeros in a thousand, however this can also be thought of as moving the decimal to the right three places.
Since dividing is the opposite of multiplying students should be able to make this easy jump. If we move the decimal to the right when we multiply by 10, 100, 1000, then which way would it move when we divide by 10, 100, 1000? To the left is correct. When you are dividing by 10, 100, 1000 etc. you simply have to move the decimal to the left as many times as there are zeros.
Example:
23 x 10 = 2.3 (once to the left)
23 x 100 = 0.23 (twice to the left)
23 x 1000 = 0.023 (three times to the left notice we have to add a zero to show place value)
23 x 10 000 = 0.0023 (four times and again adding zeros to show place value)